An alt-azimuth or altazimuth mounting base is a simple two-axis mounting base for supporting and rotating an instrument about two perpendicular axes, i.e., one vertical axis and one horizontal axis. Rotation about the vertical axis adjusts the azimuth (compass bearing) of the pointing direction of the instrument. Rotation about the horizontal axis changes the altitude (angle of elevation) of the pointing direction.
Conventional alt-azimuth mounting base can be described as follows:
There are two active perpendicular axes (implemented with two revolute joints) in the conventional alt-azimuth mounting base. Each joint is driven by a servo motor and gear box. This type of two-axis mounting base has the advantages of a simple structure and an easy implementation of a control module. However, this type of mounting base would be very bulky for supporting a heavy instrument.
As an improved structure for a bulky instrument, another type of alt-azimuth mounting base has a circular rail and several rollers to support the weight in the azimuth motion. However, the azimuth motion is still driven by a motor and a reducer on the vertical axis.
To sum up, it is desirable to propose a novel light structure of an alt-azimuth mounting base particularly for the heavy instrument.